Asteropeia and Physena (Caryophyllales): A case study in comparative wood anatomy

Previous analyses ofAsteropeia andPhysena have not compared the wood anatomy of these genera to those of Caryophyllales s.l. Molecular evidence shows that the two genera from a clade that is a sister group of the core Caryophyllales. Synapomorphies of theAsteropeia-Physena clade include small circular alternate pits on vessels, presence of vasicentric tracheids plus fiber-tracheids, presence of abaxial-confluent plus diffuse axial parenchyma, and presence of predominantly uniseriate rays. These features are analyzed with respect to habit and ecology of the two genera. Solitary vessels, present in both genera, are related to the presence of vasicentric tracheids. Autapomorphies in the two genera seem related to adaptations byPhysena as a shrub of moderately dry habitats (e.g., narrower vessel elements, abundant vasicentric tracheids, square to erect cells in rays) as compared to alternate character expressions that seem related to the arboreal habit and humid forest ecology ofAsteropeia. The functional significance of vasicentric tracheids and fiber-tracheids in dicotyledons is briefly reviewed in the light of wood anatomy of the two genera.     

Wood and stem anatomy of woody Amaranthaceae s.s.: ecology, systematics and the problems of defining rays in dicotyledons

Wood and stem anatomy is studied for seven species of six genera (root anatomy also reported for one species) of Amaranthaceae s.s. Quantitative data on vessels correlate closely with relative xeromorphy of respective species, agreeing with values reported for dicotyledons without successive cambia in comparable habitats. Libriform fibre abundance increases and vessel diameter decreases as stems and roots of the annual Amaranthus caudatus mature. Long, thick-walled fibres in Bosea yervamora may be related to the upright nature of elongate semi-climbing stems. Non-bordered or minutely bordered perforation plates characterize Amaranthaceae, as they do most other Caryophyllales. Amaranthaceae have idioblastic cells containing druses, rhomboidal crystals or crystal sand: these forms intergrade and seem closely related. Rays are present in secondary xylem of the Amaranthaceae studied. Cells intermediate between ray cells and libriform fibres occur in Charpentiera elliptica . Degrees of diversity in rays and reports of raylessness in Amaranthaceae induce discussion of definition and identification of rays in dicotyledons; some sources recognize both rays and radial plates of conjunctive tissue in Amaranthaceae. The action of successive cambia is described: lateral meristem periclinal divisions produce secondary cortex externally, conjunctive tissue internally and yield vascular cambia as well. Vascular cambia produce secondary phloem and secondary xylem, in both ray and fascicular zones, as in a dicotyledon with a single cambium. Identification of meristem activity and appreciation of varied ray manifestations are essential in understanding the ontogeny of stems in Amaranthaceae (which have recently been united with Chenopodiaceae).  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 1–19.     

Wood anatomy of Krameriaceae with comparisons with Zygophyllaceae: phylesis, ecology and systematics

Wood of nine species of Krameria (including all clades proposed within the genus) reveals a few characters related to infrageneric systematics; most relate primarily to ecology and habit. Wood of Krameria closely fits quantitative data reported for desert shrubs. Lack of vessel grouping correlates with the presence of densely pitted tracheids. Wood xeromorphy in Krameria may relate in part to hemiparasitism. Tracheid presence may also account for relatively low vessel density. Wood anatomy of six species of Zygophyllaceae (including both genera of Morkillioideae) is compared with that of Krameriaceae because recent phylogenies propose that these two families comprise the order Zygophyllales. Several wood characters appear to represent synapomorphies reflecting this relationship. Differences in wood anatomy between Krameriaceae and Zygophyllaceae are believed to represent autapomorphies. Notable among these include Paedomorphic Type II rays (Krameriaceae), storying (Zygophyllaceae), presence of vestured pits (Zygophyllaceae), and differentiation into vasicentric tracheids and fibre-tracheids (Zygophyllaceae). The latter feature is referable to the concept of fibre-tracheid dimorphism. Recognition of Krameriaceae as separate from Zygophyllaceae is supported by wood characters. Wood of Zygophyllales does not conflict with the idea that the order belongs to rosids, with Malpighiaceae as the outgroup of Zygophyllales.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 257–270.     

Living cells in wood. 2. Raylessness: histology and evolutionary significance

Raylessness occurs in several hundred species belonging to about 40 families (fewer depending on taxonomic delineation). Fibre distribution (raylessness at first, followed by origin of rays), fibre wall thickness and sclerenchyma at pith margins support the idea that rapid acquisition of mechanical strength is basic to most instances of raylessness. Raylessness may be the most readily available process for achieving mechanical strength in ancestrally herbaceous groups lacking large amounts of phloem and cortical fibres. Raylessness is not a uniform phenomenon and a small number of instances suggest alternative causation, as in two lianas (Cobaea, Thunbergia). Raylessness occurs in only a small number of trees and annuals, but is found in woody herbs, subshrubs and some shrubs. It is indicative of secondary woodiness and wood paedomorphosis. Raylessness would seem to block the radial flow that rays typically provide, but a surprising number of rayless woods have moderately pitted fibres (indicative of flow) and septate or non‐septate living fibres. Three‐dimensional networks of conjunctive tissues in rayless species with successive cambia (Aizoaceae, Amaranthaceae, Nyctaginaceae) could also provide radial flow avenues. Ontogenetic changes from raylessness to ray presence within the stem of a given species are described and illustrated. Pseudo‐raylessness, late‐onset raylessness and early‐onset raylessness are recognized. Systematic distribution and pertinent literature are given for known instances of raylessness and pseudo‐raylessness. Raylessness shows that wood evolution involves not merely change in the abundance and position of cell types, but also redesign and diversification in cell types. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 529–555.     

Comparative stem anatomy of Mirabilis (Nyctaginaceae)

Mirabilis, a primarily American genus of 50?C60 species almost restricted to the New World, is the most diverse within Nyctaginaceae. It not only has the greatest number of species, but also many life forms, with annual herbaceous, suffrutescent and shrubby species and with prostrate, decumbent to erect stems that are sometimes clambering. Stem anatomy has been studied only for M. jalapa, and its characteristics extrapolated to the entire genus. In this study we evaluated the taxonomic significance of stem anatomical characters from 24 species of Mirabilis, as well as their potential relation to habit evolution. Qualitative and quantitative characters of transverse and longitudinal sections were evaluated using light and scanning electron microscopy. Stem anatomy varies in several features. The phloem is arranged in short tangential spreading bands or in large tangential bands forming semi-complete rings; the conjunctive tissue is fibrous, with thin-walled sclereids and fibres, or parenchymatous; the vessels are solitary or grouped in radial multiples or clusters; the xylem fibres are very thin-walled or thin- to thick-walled with simple to minutely bordered pits; most species are raylessness; the pith has parenchyma or thin-walled sclereids or brachysclereids. The distribution of anatomical characters in Mirabilis does not correspond with the current infrageneric classification. We suggest that some stem anatomical characters are correlated with habit and that the vascular cylinder and pith characters are related to an increase in mechanical strength. This study provides new information and novel characters about the stem anatomy not only of Mirabilis, but of the family.     

Systematic and phylogenetic value of wood anatomy in Heteromorpheae (Apiaceae,Apioideae)

The wood anatomy of all four woody genera of the tribe Heteromorpheae (Apiaceae, subfamily Apioideae) has been described and compared, based on 40 wood samples (representing nine species of Anginon, one species of Glia, three species of Heteromorpha and two species of Polemannia). The four genera were found to be relatively similar in their wood anatomy. Helical thickenings on the vessel walls occur in all species investigated and appear to represent an ancestral character state and a symplesiomorphy for the tribes Bupleurieae and Heteromorpheae. Each of four genera has a diagnostically different combination of character states relating to the diameter of vessels, size of intervessel pits, length of fibres, presence and arrangement of banded axial parenchyma, size of rays and ray cells, and presence of septate fibres and crystals in the ray cells. The occurrence of marginal axial parenchyma in Anginon and Glia may be an additional synapomorphy for these taxa. Variation in the wood anatomy of 31 samples from nine species of Anginon is not correlated with habitat (Fynbos or Succulent Karoo Biomes), but instead appears to reflect adaptations to seasonal aridity found in both ecosystems. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 569–583.     

Comparative palynology and wood anatomy of <Emphasis Type="Italic">Taxodium distichum</Emphasis> (L.) Rich. and <Emphasis Type="Italic">Taxodium mucronatum</Emphasis> Ten.

A comparative study of Taxodium distichum (L.) Rich. and Taxodium mucronatum Ten. was carried out on the basis of pollen morphology and wood anatomy by light and scanning electron microscopy. We describe a detailed analysis of the anatomical characteristics of the wood, including the tracheids, ray parenchyma, axial parenchyma and number of cross-field pits. Palynological characters were also studied to reveal the shape, size and ultrastructure of the pollen grains. These studies give taxonomic support for the recognition of T. distichum and T. mucronatum as two different species.     

Wide-band tracheids in leaves of genera in Aizoaceae: the systematic occurrence of a novel cell type and its implications for the monophyly of the subfamily Ruschioideae

 Stem and leaf anatomical characters of succulent plants in families of the order Caryophyllales were examined to determine phylogenetic and evolutionary trends within these families. Wide-band tracheids, novel tracheids having wide secondary walls hypothesized to prevent cell collapse under water stress, were found in three families–Aizoaceae, Cactaceae, and Portulacaceae. Wide-band tracheids are hypothesized to be a unique adaptation to severe drought conditions prevalent in the areas of origin for these families. Species of 89 genera of Aizoaceae were examined for the occurrence of these tracheids. If present, wide-band tracheids occurred only in leaves. Of the five subfamilies examined, these tracheids were found only in the subfamily Ruschioideae, but not in the putative basal genera of the ruschioids. The presence of wide-band tracheids is an apomorphic character for genera of Ruschioideae with the exception of the basal genera, and also suggests that further characters are needed to understand the alliance of the Apatesia and Cleretum groups with other ruschioid groups. Received April 19, 2000 Accepted December 26, 2000     

The Ecological Secondary Xylem Anatomy of 7 Desert Species of Leguminosae

The wood anatomy of 7 species (Ammopiptanthus mongolicus, Amorpha fruticosa, Halimodendron halodendron, Hedysarum mongolicum. Hedysarum scoparium, Lespedeza bicolor and Robinia pseudoacacia)of Leguminosae, which grow in desert regions of Northern China, is described in details. A comparative study on the quantitative wood anatomical characters among the species is made. Except some anatomical characters in A. fruticosa were larger in vessel diameter, thin walled in vessels and libriform fibres, all the rest six species showed a general similarities:vessel frequency/sq, mm very numerous and percentage of multiple vessels high; vessel elements very short, perforations simple and in almost horizontal end walls, intervessel bordered pits alternate and vestured; libriform fibres very short, and usually with thickened walls, and with simple pits; average ray height very low, and with multiseriate as well as uniseriate. However, there are differences in other characters, e. g. vessel distribution, percentage of solitary vessels; spiral thickenings present or absent; amount of axial parenchyma and distribution; ray frequency and type; crystals present or absent, and crystal distribution, if present. According to these anatomical diversities, a key to the identification of the 7 species is given. In this article, the relation between the structure of wood and the environmental influences has been discussed.     

The earliest wood and its hydraulic properties documented in c. 407‐million‐year‐old fossils using synchrotron microtomography

We document xylem structure and hydraulic properties in the earliest woody plant A rmoricaphyton chateaupannense gen. nov. & sp. nov. based on c. 407‐million‐year‐old fossils from the Armorican Massif, western France. The plant was small, and the woody axes were narrow and permineralized in pyrite (FeS₂). We used standard palaeobotanical methods and employed propagation phase contrast X‐ray synchrotron microtomography (PPC‐SRμCT) to create three‐dimensional images of the wood and to evaluate its properties. The xylem comprised tracheids and rays, which developed from a cambium. Tracheids possessed an early extinct type of scalariform bordered pitting known as P‐type. Our observations indicate that wood evolved initially in plants of small stature that were members of Euphyllophytina, a clade that includes living seed plants, horsetails and ferns. Hydraulic properties were calculated from measurements taken from the PPC‐SRμCT images. The specific hydraulic conductivity of the xylem area was calculated as 8.7 kg m^?1 s^?1 and the mean cell thickness‐to‐span ratio (t/b)² of tracheids was 0.0372. The results show that the wood was suited to high conductive performance with low mechanical resistance to hydraulic tension. We argue that axis rigidity in the earliest woody plants initially evolved through the development of low‐density woods. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 423–437.     

WOOD ANATOMY OF TREMANDRACEAE: PHYLOGENETIC AND ECOLOGICAL IMPLICATIONS

Stems of four species of the Australian family Tremandraceae furnished sufficient material for analysis of wood anatomy. Presence of simple perforation plates on vessel elements, occurrence of libriform fibers (some septate), tendency toward vasicentric parenchyma, presence of crystalliferous axial parenchyma strands, presence of crystals singly in ray cells, and occurrence of amorphous deposits in parenchyma are all features in which Tremandraceae resemble Pittosporaceae. Wood anatomy tends to support a “rosoid” rather than a sapindalean, rutalean, or polygalalean affinity for Tremandraceae, although wood is only a preliminary indicator. By the use of numerical indices as well as such indicators as helical thickening and presence of vascular tracheids, wood of Tremandraceae is shown to be highly xeromorphic. The genus Tremandra may represent a secondary entrant into wet forests of southwestern Australia; it clearly is not relict from mesic ancestry.     

Wood anatomy of Polygonaceae: analysis of a family with exceptional wood diversity

Quantitative and qualitative data are presented for woods of 30 species of woody Polygonaceae. Wood features that ally Polygonaceae with Plumbaginaceae include nonbordered perforation plates, storeying in narrow vessels and axial parenchyma, septate or nucleate fibres, vasicentric parenchyma, pith bundles that undergo secondary growth, silica bodies, and ability to form successive cambia. These features are consistent with pairing of Plumbaginaceae and Polygonaceae as sister families. Wood features that ally Polygonaceae with Rhabdodendraceae include nonbordered perforation plates, presence of vestured pits in vessels, presence of silica bodies and dark-staining compounds in ray cells, and ability to form successive cambia. Of the features listed above, nonbordered perforation plates and ability to form successive cambia may be symplesiomorphies basic to Caryophyllales sensu lato . The other features are more likely to be synapomorphies. Wood data thus support molecular cladograms that show the three families near the base of Caryophyllales s.l. Chambered crystals are common to three genera of the family and may indicate relationship. Ray histology suggests secondary woodiness in Antigonon, Atraphaxis, Bilderdykia, Dedeckera, Eriogonum, Harfordia, Muehlenbeckia, Polygonum , and Rumex . Other genera of the family show little or no evidence of secondary woodiness. Molecular data are needed to confirm this interpretation and to clarify the controversial systematic groupings within the family proposed by various authors. Vessel features of Polygonaceae (lumen diameter, element length, density, degree of grouping) show an extraordinary range from xeromorphy to mesomorphy, indicating that wood has played a key role in ecological and habital shifts within the family; the diversity in ecology and habit are correlated with quantitative wood data.  © 2003 The Linnean Society of London. Botanical Journal of the Linnean Society , 2003, 141 , 25−51.     

Variation in wood anatomical traits of Pinus sylvestris L. between Spanish regions of provenance

The Spanish populations of Pinus sylvestris L. occupy differentiated sites and must therefore include structural variations to cope with varied climate conditions. This study compares wood anatomical traits of P. sylvestris from ten Spanish regions of provenance with contrasting climates, taking into account the effects of region of provenance and tree nested within provenance on variation in wood biometry. In general, the effect of both sources of variation (provenance and tree) on wood biometry was highly significant. Most of the anatomical variations observed were intra-populational (at the tree level), although variation explained by provenance was high for some parameters (e.g., ray frequency and ray parenchyma cell frequency), suggesting high environmental influence. Trees in the driest region, growing in a Mediterranean phytoclimate, were characterized by large tracheid lumens, suggesting more efficient water conduction. They also had thick cell walls, which would reduce the risk of cavitation caused by high implosion stress during periods of drought, as well as a high ray tracheid frequency, implying greater water storage capacity in the sapwood. The population with greatest growth, located in an oroboreal phytoclimate, was characterized by large bordered pits and long tracheids, which would reduce resistivity in water transport. At higher altitudes, tracheid lumen diameter and resin canal diameter tended to be smaller, and intertracheid wall strength was greater. Results are discussed in relation to adaptation of the species to growth demands and frost.     

Structural analysis of K<Superscript>+</Superscript> dependence in <Emphasis Type="SmallCaps">l</Emphasis>-asparaginases from <Emphasis Type="Italic">Lotus japonicus</Emphasis>

Wood is composed of various types of cells and each type of cell has different structural and functional properties. However, the temporal and spatial diversities of cell wall components in the cell wall between different cell types are rarely understood. To extend our understanding of distributional diversities of cell wall components among cells, we investigated the immunolabeling of mannans (O-acetyl-galactoglucomannans, GGMs) and xylans (arabino-4-O-methylglucuronoxylans, AGXs) in ray cells and pits. The labeling of GGMs and AGXs was temporally different in ray cells. GGM labeling began to be detected in ray cells at early stages of S₁ formation in tracheids, whereas AGX labeling began to be detected in ray cells at the S₂ formation stage in tracheids. The occurrence of GGM and AGX labeling in ray cells was also temporally different from that of tracheids. AGX labeling began to be detected much later in ray cells than in tracheids. GGM labeling also began to be detected in ray cells either slightly earlier or later than in tracheids. In pits, GGM labeling was detected in bordered and cross-field pit membranes at early stages of pit formation, but not observed in mature pits, indicating that enzymes capable of GGM degradation may be involved in pit membrane formation. In contrast to GGMs, AGXs were not detected in pit membranes during the entire developmental process of bordered and cross-field pits. AGXs showed structural and depositional variations in pit borders depending on the developmental stage of bordered and cross-field pits.     

Do tracheid microstructure and the presence of minute crystals link Nymphaeaceae,Cabombaceae and Hydatellaceae?

Original scanning electron microscopy (SEM) observations are presented for stems of Brasenia schreberi and Cabomba caroliniana of Cabombaceae and three species of Trithuria of Hydatellaceae. End walls of stem tracheids of Brasenia have the same peculiar microstructure that we have reported in Barclaya, Euryale, Nuphar, Nymphaea (including Ondinea) and Victoria of Nymphaeaceae. This feature unites Cabombaceae with Nymphaeaceae. The minute rhomboidal crystals on the surfaces of stellate parenchyma cells of Brasenia reported by Solereder (1906. Oxford: University Press), but not noticed since, are figured. They are like the minute crystals of the often‐mentioned astrosclereids of Nymphaeaceae. Neither of these two features has been observed in Hydatellaceae. If the absence of these two features can be confirmed, the reason may be more related to ecology, development, habit and anatomical organization than to degree of phylogenetic relationship as shown by molecular studies. Anatomical observations on the stem anatomy of Trithuria are offered on the basis of paraffin sections prepared for a paper by Cheadle & Kosakai (1975. American Journal of Botany 62: 1017–1026); that study is notable for a discrepancy between an illustration of a specialized vessel element on the one hand and tabular data indicating long scalariform perforation plates on the other. Long scalariform perforation plates are mostly found in scalariformly pitted vessels of monocots, whereas the tracheary elements of Trithuria mostly have helical or annular thickenings. We were unable to demonstrate the presence of vessels in Hydatellaceae. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 572–582.     

Leaf anatomy of Ficus subsection Urostigma (Moraceae)

Species of Ficus subsection Urostigma show much overlapping variation in vegetative morphology, which often precludes correct identification of the species. The aim of this study was to describe the leaf anatomical characters and their variation and to check their suitability for identification. Included were 41 samples belonging to 25 species of subsection Urostigma, four samples belonging to two species of section Leucogyne and one specimen of Ficus glaberrima subsp. siamensis of subsection Conosycea. Transverse sections of lamina, midrib and petiole and cuticular macerations were used, and the observed anatomical characters are described for each species. On the basis of a limited number of studied samples, leaf anatomy shows little variation within each species and each species has a unique combination of character states, facilitating identification. Ficus arnottiana shows some leaf anatomical characters that are quite different from those of other members of subsection Urostigma, including a multiple epidermis and enlarged lithocysts on both sides of the leaf. Both characters are generally considered as typical for Ficus subsection Conosycea. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 259–281.     

Adulthood and phylogenetic analysis in gastropods: character recognition and coding in shells of Lavigeria (Cerithioidea, Thiaridae) from Lake Tanganyika

In the study of gastropod shell morphology, determination of comparable ontogenetic stages is crucial, because all the states that various shell features go through during ontogeny are preserved on the shell. The protoconch/teleoconch transition and marks of episodic growth are among the few ways of defining discrete, comparable, growth stages. In gastropods with determinate growth the attainment of adulthood may provide additional shell markers permitting comparison among individuals and taxa. Adulthood is reflected in shell morphology in ways as diverse as shell deposition covering all the previous whorls and radically changing the shape of the shell through to slight changes in the trajectory of the suture. While the very prominent adulthood‐related changes of shell morphology have been used as systematic characters, the more moderate changes have not been studied in detail and their potential systematic value has been ignored. In this paper we give a detailed account of adult modifications of the shell appearing with cessation of growth. Our study group comprises eight closely related species of Lavigeria from Lake Tanganyika. We show that the ways adulthood is manifested are quite diverse. We describe eight characters of the aperture, the suture and the sculptural ornamentation. Character occurrence varies greatly among species. We show that characters appear in suites and that in many cases their appearance is connected to size. We use size as a proxy for adulthood and test whether character occurrence alone or its connection to size can help resolve species relationships. In both cases our characters confirm the monophyly of our ingroup and yield cladograms with various degrees of resolution of ingroup relationships. The coding method that yields the greater character congruence is the one that takes into consideration the connection between appearance of a character and size. This study demonstrates that ontogenetically correlated character transformations may nevertheless be phylogenetically independent. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140 , 223?240.     

Morpho‐anatomical diversity of the underground systems of Arrojadoa (Cactaceae), an endemic Brazilian genus

Members of Arrojadoa exhibit a variety of underground structures that can originate from roots or stems. Although the development of underground structures of stem origin in Arrojadoa represents a unique trait among Cactaceae of eastern Brazil, no detailed reports on the morphological diversity of such structures are available. The present morpho‐anatomical study of the underground systems of Arrojadoa has demonstrated that a single species can exhibit one or more structural types, such as single or branched stem tubers, short thick stems and/or long subterranean stems, thick and fleshy contractile roots and normal fibrous roots. Various morpho‐anatomical structures relating to the underground storage systems in Arrojadoa spp. have also been observed, including thick contractile roots consisting mainly of secondary xylem formed by fibrous wood with wide‐band tracheids (WBTs) and underground stems with a wide cortical region and WBTs‐type wood. Based on the evidence presented, we suggest that such traits, together with the occurrence of contractile roots associated with underground stems, are important adaptive strategies for the survival of the plants during seasonal drought in areas of cerrado (savannah), campo rupestre (rocky uplands) and caatinga (dry thorny scrubland). © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 108–128.     

Living Cells in Wood 3. Overview; Functional Anatomy of the Parenchyma Network

The very different evolutionary pathways of conifers and angiosperms are very informative precisely because their wood anatomy is so different. New information from anatomy, comparative wood physiology, and comparative ultrastructure can be combined to provide evidence for the role of axial and ray parenchyma in the two groups. Gnetales, which are essentially conifers with vessels, have evolved parallel to angiosperms and show us the value of multiseriate rays and axial parenchyma in a vessel-bearing wood. Gnetales also force us to re-examine optimum anatomical solutions to conduction in vesselless gymnosperms. Axial parenchyma in vessel-bearing woods has diversified to take prominent roles in storage of water and carbohydrates as well as maintenance of conduction in vessels. Axial parenchyma, along with other modifications, has superseded scalariform perforation plates as a safety mechanism and permitted angiosperms to succeed in more seasonal habitats. This diversification has required connection to rays, which have concomitantly become larger and more diverse, acting as pathways for photosynthate passage and storage. Modes of growth such as rapid flushing, vernal leafing-out, drought deciduousness and support of large leaf surfaces become possible, advantaging angiosperms over conifers in various ways. Prominent tracheid-ray pitting (conifers) and axial parenchyma/ray pitting to vessels (angiosperms) are evidence of release of photosynthates into conductive cells; in angiosperms, this system has permitted vessels to survive hydrologic stresses and function in more seasonal habitats. Flow in ray and axial parenchyma cells, suggested by greater length/width ratios of component cells, is confirmed by pitting on end walls of elongate cells: pits are greater in area, more densely placed, and are often bordered. Bordered pit areas and densities on living cells, like those on tracheids and vessels, represent maximal contact areas between cells while minimizing loss of wall strength. Storage cells in rays can be distinguished from flow cells by size and shape, by fewer and smaller pits and by contents. By lacking secondary walls, the entire surfaces of phloem ray and axial phloem parenchyma become conducting areas across which sugars can be translocated. The intercontinuous network of axial parenchyma and ray parenchyma in woods is confirmed; there are no “isolated” living cells in wood when three-dimensional studies are made. Water storage in living cells is reported anatomically and also in the form of percentile quantitative data which reveal degrees and kinds of succulence in angiosperm woods, and norms for “typically woody” species. The diversity in angiosperm axial and ray parenchyma is presented as a series of probable optimal solutions to diverse types of ecology, growth form, and physiology. The numerous homoplasies in these anatomical modes are seen as the informative results of natural experiments and should be considered as evidence along with experimental evidence. Elliptical shape of rays seems governed by mechanical considerations; unusually long (vertically) rays represent a tradeoff in favor of flexibility versus strength. Protracted juvenilism (paedomorphosis) features redirection of flow from horizontal to vertical by means of rays composed predominantly or wholly of upright cells, and the reasons for this anatomical strategy are sought. Protracted juvenilism, still little appreciated, occurs in a sizeable proportion of the world’s plants and is a major source of angiosperm diversification.     

Leaf morphology and anatomy of Camellia section Camellia (Theaceae)

The delimitations of species in Camellia section Camellia have been disputed for many years, resulting from uncertain relationships among species. Leaf morphological and anatomical characters for 54 species and three varieties in this section were investigated to reveal the relationships. Principal component analysis and cluster analysis were conducted using the transformed data for quantitative and qualitative characters from leaf morphology and anatomy. Combining the results of statistical analysis with comparative leaf characters of morphology and anatomy, we discussed the taxonomic treatment of section Camellia by Chang compared with that of Ming and we conclude that section Camellia consists of c. 50 species. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 456–476.